The impact of faster antimicrobial susceptibility testing report and dual antimicrobial susceptibility testing cards on the antibiotic therapy and economics of hospitalized bloodstream infection patients.

BACKGROUND

Overuse of carbapenems and other broad-spectrum antibiotics increases both costs and the risk of antimicrobial resistance (AMR). This study assessed whether optimizing antimicrobial susceptibility testing (AST) reports could improve clinical and economic outcomes for hospitalized patients with bloodstream infections (BSIs).

METHODS

From June 2022 to May 2023, a series of microbiology laboratory interventions were implemented at the Affiliated Hospital of North Sichuan Medical College, including the use of BacT/Alert Virtuo system (bioMérieux, France) for rapid loading, VITEK MS (bioMérieux, France) for rapid microbiology identification (ID), 24-hour laboratory service, and dual AST cards (N335 + XN04) replacing the single card (GN13). Previous simultaneously reported ID and AST results were successfully replaced by a separate reporting process. Data from BSI patients before (June 2021-May 2022) and after (June 2023-May 2024) interventions were retrospectively analyzed for ID and AST reporting time, antibiotic use, length of stay (LOS), and costs.

RESULTS

A total of 256 BSI patients were analyzed (125 pre-intervention; 131 post-intervention). The post-intervention group had significantly shorter times to ID (median 41.26 vs. 74.35 h) and AST reports (56.02 vs. 74.35 h), with earlier opportunities for targeted antibiotic adjustments. Antibiotic modifications occurred ~ 36 h sooner within the first 72 h. Among all agents, carbapenems underwent the most MIC-based changes (20 additions and 10 discontinuations), reflecting improved carbapenem stewardship driven by expanded AST coverage. Post-intervention patients also showed shorter LOS, reduced antibiotic and testing costs, and a potential improvement in survival, especially in ICU cases.

CONCLUSIONS

Optimized microbiology workflows, including dual AST cards and faster AST report, significantly accelerated reporting and facilitated timely, precise antimicrobial therapy, particularly carbapenem stewardship, while reducing clinical and economic burdens.